In this proposal, we describe a collaborative, predoctoral interdisciplinary training program that will produce scholars who will receive rigorous grounding in an academic discipline (health economics, policy analysis, or organizational theory) and who will acquire extensive training and research experience in addiction. The proposal builds on the considerable strengths of current teaching, clinical, and research enterprises at Yale University. We link state-of-the-art methods with some of the nation's leading clinical and research experts in addiction. The primary focus will be on illicit drugs, tobacco and HIV/AIDS as a critical comorbidity occurring with HIV/AIDS. Our request for the next 5 years is for 4 predoctoral positions. Students will enroll in a well-established PhD program in the Health Policy and Administration (HPA) division at Yale School of Public Health. Students will be trained through formal classes, seminars, and mentored research. Each student will be required to obtain expertise in a disciplinary area: health economics, policy analysis or organizational theory, as well as econometrics and biostatistics. Ethical conduct is taught and required for the trainees. They will also learn about addiction in the Division of Substance Abuse (DSA) in Psychiatry at the Yale School of Medicine, as well as through an integrative course taught by Dr. Sindelar. Students will attend existing comprehensive addiction research seminars in DSA and participate in an expanded version of a current course on addiction policy offered by Dr. Sindelar. Two seminars in health services research in HPA will also be required. This curriculum will uniquely prepare students for a career in addiction health services research. Faculty mentors on this proposal have outstanding productivity in research, external funding, teaching, mentoring and training predoctoral and postdoctoral fellows. Many have long-term, productive collaborations with each other through research centers. Thirty mentors have been selected primarily from HPA and DSA. Trainees will be required, and have ample opportunities, to apply their interdisciplinary training to ongoing research in substance abuse treatment, addiction health services research and policies applied to addiction. By attracting a diverse group of high-quality, motivated, predoctoral trainees and providing them in-depth training, excellent mentoring and a rich, interdisciplinary research environment, we expect to produce the next generation of experts in addiction health economics, health services research, and policy analysis. Trainees will produce research that is policy-oriented, population-based and addresses both prevention and treatment, with a goal of improving lives of addicted individuals and reducing the negative impact of addiction on society. Note that while there are multiple training programs at Yale, there is no doctoral-level training program at Yale focused specifically on health economics, policy analysis, and organizational theory as applied to addicted populations.